Analysis and hypothesis testing of redundant energy of solar home systems without net-metering

Solar home systems (SHS) are increasing being deployed as sustainable energy supply for the residential sector to meet the Sustainable Development Goal 7 target by 2030, especially for countries in sub-Saharan Africa (SSA) where national grid electricity supply is inadequate or weak. For SHS in SSA, however, a unique challenge exists as many of the households do not have access to net-metering system that allows extra PV energy generation during the daytime to be exported to the grid. This leads to waste energy generation (redundant energy) when the household energy demand is lower than the PV energy generation. In this study, analysis has been conducted to determine the magnitude of redundant energy of 3 SHS. Hypothesis testing of the existence of redundant energy from the SHS is also conducted. Our study has revealed that generally, there is redundant energy generation in the hours of 10 a.m. to 3 p.m. for the households, with hourly values ranging from 0.37 kWh to 1.55 kWh. The redundant energy represents 29.6 %–56.3 % of the households' monthly PV energy generation. The findings of this study give insights into the potential of harnessing redundant energy of SHS for planning smart energy cities if net-metering systems were available.